The Search for Chemical Complexity in Protoplanetary Disks: ALMA Wideband Preview of HL Tauri

Planets form in the so-called protoplanetary disks in the first few Myr since the formation of stars. The study of the chemical content of protoplanetary disks is thus essential to understand the pristine composition of planetary atmospheres and surfaces, and the chemical budget available for the possible emergence of life. In the context of the preparations for the Wideband Sensitivity Upgrade (WSU), the Acatama Large Millimiter and sub-millimiter Array has acquired a demonstration dataset, the largest ever produced of any protoplanetary disk, consisting of 32 separate observations of the HL Tauri disk with high angular and spectral resolution. In this thesis I analyze the dataset with the aims to investigate the chemical composition of the HL Tau disk, especially in relation to the late accretion events described in the literature, which are thought to favor the enrichment of the gas phase with S-bearing molecules. I find sixteen line detections at high confidence belonging to nine molecules, namely four isotopologues of CO, HCO+, CN, HCN, HNC, and SO, originating from three spatially distinct regions of the HL Tau system. I derive spatial and line properties and compare them with those found in the literature. I derive column densities and temperature of SO using additional detections from the literature, better constraining them and confirming the origin of the molecule in relation to late accretion events. I also perform an analysis of the continuum emission of HL Tau, deriving the SED and the spectral index map.